Shading decreases the abundance of the herbivorous California horn snail, Cerithidea californica

Journal of Experimental Marine Biology and Ecology
By:  and 



Most of the intertidal zone in estuaries of California, USA and Baja California, Mexico is covered with vascular vegetation. Shading by these vascular plants influences abiotic and biotic processes that shape benthic community assemblages. We present data on the effects of shading on the California horn snail, Cerithidea californica. This species is important because it is the most common benthic macrofaunal species in these systems and acts as an obligate intermediate host of several species of rematode parasites that infect several other species. Using observational and experimental studies, we found a negative effect of shade on the distribution and abundance of the California horn snail. We hypothesized that shading reduces the abundance of the epipelic diatoms that the snails feeds on, causing snails to leave haded areas. We observed a negative relationship between vascular plant cover, sub-canopy light levels, and snail density in Mugu Lagoon. Then we experimentally manipulated light regimes, by clipping vegetation and adding shade structures, and found higher snail densities at higher light levels. In Goleta Slough, we isolated the effect of shade from vegetation by documenting a negative relationship between the shade created by two bridges and diatom and snail densities. We also found that snails moved the greatest distances over shaded channel banks compared to unshaded channel banks. Further, we documented the effect of water depth and channel bank orientation on shading in this system. An additional effect of shading is the reduction of temperature, providing an alternative explanation for some of our results. These results broaden our knowledge of how variation in the light environment influences the ecology of estuarine ecosystems.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Shading decreases the abundance of the herbivorous California horn snail, Cerithidea californica
Series title Journal of Experimental Marine Biology and Ecology
DOI 10.1016/j.jembe.2012.07.009
Volume 432-433
Year Published 2012
Language English
Publisher Elsevier
Contributing office(s) Western Ecological Research Center
Description 8 p.
First page 148
Last page 155
Country United States
State California
County Santa Barbara County;Ventura County
Other Geospatial Goleta Slough;Mugu Lagoon
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